diff --git a/news/changelog-1.6.md b/news/changelog-1.6.md
index b4c24baa57..2d4b8a89d6 100644
--- a/news/changelog-1.6.md
+++ b/news/changelog-1.6.md
@@ -11,6 +11,7 @@ All changes included in 1.6:
 
 ## Lua Filters and extensions
 
+- ([#8179](https://github.com/quarto-dev/quarto-cli/issues/8179)): When merging code cells for complex layouts, do not merge cells with different languages.
 - ([#10004](https://github.com/quarto-dev/quarto-cli/issues/10004)): Resolve callout titles, theorem names, and `code-summary` content through `quarto_ast_pipeline()` and `process_shortcodes()`.
 - ([#10196](https://github.com/quarto-dev/quarto-cli/issues/10196)): Protect against nil values in `float.caption_long`.
 - ([#10328](https://github.com/quarto-dev/quarto-cli/issues/10328)): Interpret subcells as subfloats when subcap count matches subcell count.
diff --git a/src/resources/filters/layout/layout.lua b/src/resources/filters/layout/layout.lua
index 8d08bfe0b5..dd49f3a4bb 100644
--- a/src/resources/filters/layout/layout.lua
+++ b/src/resources/filters/layout/layout.lua
@@ -86,8 +86,16 @@ function partition_cells(float)
   end
 
   local function handle_preamble_codeblock(block)
-    if block.t == "CodeBlock" and #preamble > 0 and preamble[#preamble].t == "CodeBlock" then
-      preamble[#preamble].text = preamble[#preamble].text .. "\n" .. block.text
+    if #preamble == 0 then
+      preamble:insert(block)
+      return
+    end
+    local last = preamble[#preamble]
+    if block.t == "CodeBlock" and 
+      last.t == "CodeBlock" and
+      -- https://pandoc.org/lua-filters.html#pandoc.list:__eq
+      last.classes == block.classes then
+      last.text = last.text .. "\n" .. block.text
     else
       preamble:insert(block)
     end
diff --git a/tests/docs/smoke-all/2024/10/08/issue-8179.qmd b/tests/docs/smoke-all/2024/10/08/issue-8179.qmd
new file mode 100644
index 0000000000..9721046e2a
--- /dev/null
+++ b/tests/docs/smoke-all/2024/10/08/issue-8179.qmd
@@ -0,0 +1,76 @@
+---
+title: "Block layout"
+format: html
+engine: knitr
+keep-md: true
+_quarto:
+  tests:
+    html:
+      ensureHtmlElements:
+        - 
+          - "pre.r"
+          - "pre.python"
+        - []
+---
+
+
+
+
+# Code chunk block layout
+
+:::: {layout="[48,-4,48]"}
+
+::: {}
+
+### R
+
+
+
+::: {.cell}
+
+```{.r .cell-code}
+sqrt(2)
+```
+
+::: {.cell-output .cell-output-stdout}
+
+```
+[1] 1.414214
+```
+
+
+:::
+:::
+
+
+
+:::
+
+::: {}
+
+### Python
+
+
+
+::: {.cell}
+
+```{.python .cell-code}
+import math
+math.sqrt(2)
+```
+
+::: {.cell-output .cell-output-stdout}
+
+```
+1.4142135623730951
+```
+
+
+:::
+:::
+
+
+
+:::
+
+::::
\ No newline at end of file